Vehicles in a vehicular ad-hoc network (VANET) broadcast beacons giving safety-related and traffic information. In an open-access environment, this means that the VANET is susceptible to security and privacy issues. In this paper, we propose a new pseudo-identity-based scheme for conditional anonymity with integrity and authentication in a VANET. The proposed scheme uses a pseudonym in the joining process with the roadside unit (RSU) to protect the real identity even from the RSU, in case it is compromised. All previous identity-based schemes have been prone to insider attackers, and have not met the revocation process. Our scheme resolves these drawbacks as the vehicle signs the beacon with a signature obtained from the RSU. Our scheme satisfies the requirements for security and privacy, and especially the requirements for message integrity and authentication, privacy preservation, non-repudiation, traceability, and revocation. In addition, it provides conditional anonymity to guarantee the protection of an honest vehicle's real identity, unless malicious activities are detected. It is also resistant to common attacks such as modification, replay, impersonation, and man-in-the-middle (MITM) attacks. Although the numerous existing schemes have used a bilinear pairing operation, our scheme does not depend on this due to the complex operations involved, which cause significant computation overhead. Furthermore, it does not have a certification revocation list, giving rise to significant costs due to storage and inefficient communication. Our analysis demonstrates that our scheme can satisfy the security and privacy requirements of a VANET more effectively than previous schemes. We also compare our scheme with the recently proposed schemes in terms of communication and computation and demonstrate its cost-efficiency and appropriateness in working with the VANET. Meanwhile, the computation costs of the beacon signing and verification in our scheme are reduced by 49.9% and 33.3%, respectively.

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As a new product of high‐value utilization of lignin, lignin micro/nano particles (LMNPs) have attracted the attention of researchers due to their non‐toxicity, corrosion‐resistance, UV resistance, and other excellent characteristics and potential application value. This article outlined the main preparation methods of LMNPs at the current stage, summarized and compared them from three perspectives of preparation technology, final product state and product composition. Subsequently, based on the different focuses of the properties of LMNPs, their application research progress as fillers, UV blockers, drug delivery carriers, among others, were introduced. Then a concise analysis of the technical and economic assessment and life cycle assessment of LMNPs in the process of industrialization was made. Finally, the main problems at present and the future development directions were analyzed and prospected to provide references for the deep processing of forest resources and the development of bio‐based nanomaterials.

In this paper, we study an area localization problem in large scale underwater wireless sensor networks (UWSNs). The limited bandwidth, the severely impaired channel and the cost of underwater equipment all make the underwater localization problem very challenging. Exact localization is very difficult for UWSNs in deep underwater environment. We propose a range free method based on mobile detachable elevator transceiver (DET) and 3D multi-power area localization scheme (3D-MALS) to address the challenging problem. In the proposed scheme, the ideas of 2D multi-power area localization scheme (2D-ALS) and utilizing DET are used to achieve the simplicity, location accuracy, scalability and low cost performances. The DET can rise and get down to broadcast its position. And it is assumed that all the underwater nodes underwater have pressure sensors and know their z coordinates. We evaluate the performances of 2D-ALS and our proposed 3D-MALS schemes under both ideal and non-ideal channel propagation conditions, in terms of localization error and localization ratio. The simulation results show that our proposed scheme is much more efficient than the 2D-ALS.

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Vehicles authentication, the integrity of messages exchanged, and privacy-preserving are essential features in vehicular ad hoc network (VANETs) security. Most of the previously proposed VANETs security solutions do not sufficiently satisfy the security and efficiency requirements. Besides, most of those solutions are heavily dependent on the system key and long-term sensitive data stored in an ideal tamperproof device, which may not be practical or ideal for resource-constrained onboard units (), especially in the case of an unexpected cloning or physical attack. Therefore, a robust authentication solution should consider those security issues and the nature of resource-constrained nodes. To satisfy all these requirements, we propose a lightweight multi-factor authentication and privacy-preserving security solution for VANETs. It employs a combination of physically unclonable functions () and one-time dynamic pseudo-identities as authentication factors. Furthermore, it eliminates the heavy dependency on the system key by decentralising the wide precinct of the certificate authority () into regional domains and achieves robust control of domains keys. A detailed analysis demonstrates that our scheme efficiently meets the VANETs security requirements, and offers more suitable communication and computation costs and features than existing schemes.

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